Tuning mechanism



Feb. 29, 1944. 1 FIGHTER ET AL V 2,342,851

s TUNING MECHANISM y V12413.29, 1944. FIGHTER' ETA; 2,342,851

TUNING IVIECI'UUUS1VI Filed May 19, 1941 2 sheets-sheet'z Snventors 11 w M 9L Gttornegs Patented Feb. 29, 19M

TUNING MECHANISM Ludwig Fichtcr and Edward Kaegi. Kokomo, Ind.,

assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application May 19. 1941, Serial No. 394,071 y 'l Claims. (Cl. 7410) This application refers to automatic indexing mechanism and more particularly to mechanism usedvfor tuning a radio receiver to certain predetermined stations.

It has recently become very popular to provide f with the commercial radio receiver buttons or levers, as the case may be, which are merelyvforced into a predetermined position and by such action There are, of course, only a few stations from which a listener ordinarily receives programs and most of these are usually local stations. Therethe receiver istuned to a certain set station.

fore,-by supplying ,four or flve of these so-called push-button assemblies, the user is enabled to obtain, by merely pressing on one of the buttons, his favorite station. Y I

It is also necessary to provide some means for altering the set-up station as the owner maydesire to change his station set-ups from. time to time.

It is therefore an object of our invention to provide an automatic tuning device for. indexing a radio receiver.

It is a further object of our invention to provide a simple and rugged mechanism for indexing a radio receiver. A

It is a still further object of our invention to provide an automatic tuning device that can easily be adjusted to other settings.

With these and other objects in view, the embodiments of our -invention will be best understood by reference to the following specification and claims and the illustrations in the accompanying drawings, in which:

Figure 1 is a vertical sectional view of a device embodying our invention, taken on line I--I of Figure 2: f

Figure2isa of Figure 1;

Figure 3 is a view of a modified form of our invention, showing only parts of the construction:

Figure 4 shows a modified form of operating the ratchet means of our invention; and

Figure 5 shows a modied form oi' manually adjusting the tuning mechanism.

Referring now more specifically to Figure 1, there is disclosed schematically a coil 2 which is intended to be one of .the coils of a radio receiver, the inductance of which it is desired to alter in order to change the tuning of the receiver. There will, of course, be a plurality of these coils into which their associated cores such as 4 will be adjustably positioned to tune the entire receiver,

sectional view taken on line 22 ample. In order to tune the receiver therefore to diiferent stations. the cores 4 are placed at diiferent positions with respect to -their associated coils and in order to place these at certain desired points the following apparatus is pro'- vided.

A casing C surrounds and `supports the tuning mechanism, as well as the coil and core assemblies. As shown here for illustrative purposes, the core 4 which is moved with respect to the coil is adiustably pivoted to one end of a lever 8. This lever is pivoted at l0 to a rigid bar i2 fastened to the housing 6. There is pivotally con` f nected to the opposite end of the 'lever 8 a transverse bar i4 and it will thus be evident that any longitudinal movement of this bar i4 will cause the lever l to pivot and move the core 4 in and out of its associated coil. The bar I4 is supported by any suitable means such as the two arms i8 which have openings therethrough so that the bar may be slid back and forth longitudinally.

Mounted on the bar 'are a pair of horns I8 and l2in, the forwardly projecting, portions or which extend in divergent directions to form a V between the two. This assembly is clamped securely to the bar i4 by any desired means so that any force applied to the arms of the horns willl Mounted adjacent the construction already described is a large pivoted drum, the ends of which are formed of two circular plates 28, each of which has projecting from the outer face thereof a stub shaft 28 which is trunnioned in only one, however, being here shown as an cx- Il suitable supporting means in the casing 6. One of the stub s`hai`ts128 has secured thereto a ratchet wheel I0 and is therefore adapted to cause rotation of the drum assembly as the ratchet wheel is rotated by 'suitable means. Uniformly spaced at points around the periphery of each of the plates there are rotatably supported a series of threaded shafts l2 which are trunnioned in openings in the discs 26 and extend the full distance between the same. Applied to one end of each there is a small spur gear 34, the rotation of which will cause the threaded shafts to rotate. Adjacent each of the threaded shafts is a stationary shaft Il which also extends between the two plates 2e and is rigidly secured to each. This strengthens the assembly and at the same time acts as a stop for a traveling nut Aassembly 3l which is applied to each threaded shaft and adapted to be adjusted across the axis of the drum.

Each of these traveling nut assemblies I8 has a projecting portion such as 48 which contacts with the shafts 38 to prevent the rotation of the traveling nut assembly about the axis of the I threaded shaft, but allow axial movement therealong. It will thus -be evident that as the gears 34 are caused to rotate, the traveling nut assem-` blies 38 will move back and forth across the threaded shaft to a certain desired setting. Each traveling nut assembly 88 is brought to a cylindrical stub section 42 which is adapted to lie between the projecting arms 22 and 24' of the yoke member at certain positions. There are here shown six of these threaded shafts 82 supported adjacent the periphery of the drum and these correspond, of course, to six settings so that the receiver may have a plurality of predetermined stations to which it may be tuned. The yoke arms 22 and 24 lie adjacent the periphery of the drum at one point of its periphery and in such a manner that as the projecting stud portions 42 of the traveling nut assemblies 38 approach them, they will be contacted by one stud at a time and moved longitudinally, depending upon the setting of the traveling nut assembly, until the stud enters the throat of the yoke. Thereafter the stud 42 will be allowed to pass through the arms inasmuch as it can pass under the bar I4 and the assembly will be ready to receive the next stud 42 as the drum rotates. In order to allow the stud to give an accurate indexing and still allow the same to pass through between the arms 22 and 24 during the following operation as the next approaches, there is provided means whereby the yoke member 2li may be moved slightly to one side and this is possible due to the insertion of a iiat spring 44 between the arm and a stationary block 46 on the bar i4.

Projecting inwardly from the case 8 and at right angles to the drum there is trunnioned a short shaft 48 on the outer end of which there is provided a suitable manual knob 58 for rotating the same. This shaft has a plurality of peripheral grooves 52 therein which cooperate with a snap spring 84 also carried lby the casing whereby the shaft may assume different axial positions with respect to the casing and still be rotated. On the inner end of this shaft 48 there is carried a gear 86 which is adapted to cooperate with the gears 34 on the ends of the threaded shafts.

When the shaft 48 is in its outermost position, or

that shown in Figure l, the gears will not mesh, but the drum may be rotated freely and the yoke indexed to predetermined stations. However, if it is desired to reset any of the stations, the shaft 48 may be pressed inwardly, snapping the spring 54 into the outermost groove which places the gear 58 in engagement with whatever gear 34 happens to be in indexing position. Then, by rotating the manual knob 50, the gears 58 and 34 will mesh and rotate and the traveling nut assembly 38 on that particular threaded shaft will be caused to be moved back and forth, which action will 85 cause the bar i4 to slide and the set to be tuned. When the tuning point has been obtained, the manual button '50 may be retracted to pull the shaft 48 back to the position shown.

It will be noted that one of the gears 34 is larger in diameter than the remaining gears 84 and is so designed that it will mesh with the manually operated gear whenever it is in indexing position without the necessity of forcing the manual shaft 48 inward. Thus when the operator wishesto manually tune the set, he may press the button 82 a requisite number of times until the manual shaft is in indexing position and then tune through rotation of the manual knob 50. While any desired means may be used for rotating the drum assemblies to bring the different traveling nut assemblies 38 into a position to force the,yoke arms 22 and 24 to an indexed position, we have here shown merely as illustrative the actuation of such drum rotation by an electromagnet. This magnet 58 is secured to the casing 6 and has connected thereto a source of power or battery 60 and also a manually operated push button 62. The armature 84 of said magnet is connected to a pivoted link system 84 and 88, the latter-link being pivoted to the center shaft 28 of the drum. There is also pivoted upon this link a small pawl I0 which is adapted to engage with the notches I2 on the ratchet wheel 80. The link 88 also .carries a leaf spring 14 to force the pawl against the side of the ratchet wheel 80. A tension spring 18 is connected between the link v68 and the 'casing and normally biases the assembly to a position in which the armature 84 is withdrawn from the electromagnet. Therefore the energization of the latter causes the armature to be pulled downward or inward and the pawl 10 will then engage the notch l2 to cause the drum to'be rotated one-- sixth of a revolution or the distance between two of the threaded shafts, depending upon how many are provided. y

It will thus be obvious that with each energization of the electromagnet 58 the drum will be rotated a certain predetermined arcuate distance which will bring the stud portion 42 of one of the `traveling nut assemblies between the Y arms 22 and 24. As this portion rides against the Y arm, the latter will be forced to one side or the other, depending upon the location of the traveling nut, which action will cause the bar I4 to move longitudinally one way or the other and when the stud reaches the throat of the yoke, which will be the end of travel for that particular actuation, the bar I4 will be set in a definite position. 'I'his position transmitted by the lever 8 to the tuning mechanism will set that for a predetermined station. Upon the next actuation of course the stud in position will pass through the Y and the whole process will be repeated and the bar i4 set to a new position. Therefore, as the push button 62 is actuated the tuner will rotate one position and bring the receiver to the next preset station, and the stations' are brought in sequence as the button is operated and as the drum is rotated. Upon one complete rotation of the drum, al1 of the preset stations 'will be tuned in, one after the other, and also the manual tuning location and any further actuation of the button 82 will start again on the same sequence.

If it is desired to reset or adjust any of the traveling nut assemblies to a different position, the manual knob 50 can be depressed to adjust the traveling nut associated with the particular threaded shaft in juxtaposition to the yoke member at that moment. 'I'here is also provided to prevent chatter or movement of the drum once it has been indexed an indexing or locking pawl 18 which is pivoted to the casing and which is spring-biased toward the edge of one of the drum discs 26 by a leaf spring 80. The drum disc has notches 82 in its periphery into which the end A of the pawl is adapted to be depressed when an indexing position has been reached. In order'to project the locking or indexing -pawl 18 from A.fastened to a spaced projecting tip |04 on the its associated notch 82, there is provided a short pivoted arm 84 connected to the armature 64 in juxtaposition to the end of the pawl 18 and having a tapered surface which will. when the armature is withdrawn into the electromagnet, force the pawl from the notch 82 so that the drum may be rotated. This will not interfere with the locking action after the next station has been reached, for upon the withdrawal of the armature from the electromagnet by the spring 16, the pivoted arm 84 will merely rotate around its pivot and pass over the end of the pawl.

It will be noted that in the mechanism shown and described in Figures 1 and 2 that the lateral travel of the bar I4 upon which is mounted the pair of yokes 22-24, is less than the travel of the core member 4 within its associatedcoil, this motion being amplified by the lever system. There may, however, be some instances in which it is desired to have the lateral motion of thedevice actuated by the rotating studs directly drive the cores into the coils. Such a construction is shown in Figure 3 in which a coil member 2 has itsassociated core 4' directly threaded into the end of a bar I4' which is longitudinally movable, only one core-coil assembly being shown as illustrative as before. On this bar are mounted a pair. of yoke members 22-24', similar to the yokes 22-24 as shown in the tlrst instance, and mounted on the bar I4 in exactly the same manner as formerly described. However, in this instance it is necessary to have the spread be# tween the ends of the yoke members substantially twice the travel of the iron core 4 from the position in which it is entirely outside of the coil to that in which it is entirely within the coil.

In this instance the slots in the frame member through which the bar |4 runs are also provided with small rollers 86 so that the bar will be easily slidable in its longitudinal piane. The core members 4 may be threaded into the end oi.' .the bar different distances to allow for adjustments. The' adjustable studs 38 in .this instance engage the yoke members 22-24 in exactly the same manner and may be adjusted in a longitudinal plane in exactly the same way as the stud members 38 in the earlier described construction.

. If in some instances it is desired to ratchet the carrying drum mechanically instead of by the use oan electromagnet, Figure 4 discloses a possible construction for this purpose. There is shown therein an end view-of the drum assembly where the end plate 26 of the drum carfries the usual assembly of indexing studs 38. There is also mounted on the shaft 28, which is the axis for the rotation of the drum assembly, a ratchet wheel 88 which is provided to cause the drum assembly to be turned to different predetermined angles, depending upon how many station set-ups are desired. Frame members such as 90 support a longitudinal L bar 92, the short section of which is provided with a projecting tip 94 which is adapted to fit within the index notches 82 of the end plate 26 of the drum. The bar 92 is spring-biased downwardly by a coil spring 96 which surrounds one end of the bar and presses against a small disc 98 formed on the end of the bar and the frame member 90.

Pivoted on the bar 92 is a small pawl |00 having two fingers, one of which is adapted to engage the teeth of the ratchet wheel 88 and the other of which has secured thereto a short tension spring |02, the opposite end of which is` bar 92. 'This springbiases the projecting arm or the pawl |00 toward the ratchet wheel 88. Also extending outwardly from one side of the member 92 is a stop member |06 which is adapted to engage with a second ratchet wheel |08 mounted on the shaft `28 in juxtaposition to the first ratchet wheel 88. Engaging the lower surface of the end 98 of the bar 92 is one end of a pivoied lever |I0 which may 4be actuated by manual pressure. As 'the outer end is pressed down, the inner end will force'the bar 92 upwardly. This movement iirst removes the indexed tip 94 from engagement with the notch 82. It next causes the tip of` the pawl |00 to force against the ratchet wheel 88 and turn the drum assembly until the projecting stop |06 comes opposite to a tooth on the ratchet |08 which is the position of index and also stops the next index notch 82 in alignment with the projecting tip 94 so that when manual pressureris removed it will fall into this slot and again lockv the mechanism in the next position. The `.spring 96 of course returns the mechanism to its, initial condition. Thus the device may be operated either mechanically or electrically.

When the device is being operated electrically by the actuation of the electromagnet, it may be desired to usejthe same actuated button or push trunnioned in suitable supports ||6 for either* longitudinal or rotative movement.

The Shaf t is also provided with two V notches I I8 and |20, the latter having one side with much less taper than the remainder. Mounted upon the rotating rod I I2 adjacent the inner end is a gear member |22.

This rod is mounted in juxtaposition to the side of one of the rotating drum discs 26 and in such a manner that the gear member |22 may be brought into engagement with the adjusting gears 34 of thedrum assembly. Mounted just to the rear of the inner end of the shaft ||2 are a pair of contacts |24 which are connected in circuit with the controlling solenoid 58 and the supplying battery 60. Connected tothe opposite plate of the drum assembly is a small disc |26 having thereon indicating numerals so that the operator is cognizant of to what station he has the receiver tuned. Also supported on a` portion of the frame v|28 is a small spring-biased taper pin |30"`which is adapted to engage with the notches |I8 and |20 on the rotating shaftl I2.

It will thus be evident that in the device as shown the-circuit to the solenoid is open, the

contacts |24 being spaced apart. Upon axial force being applied to the shaft' I2, the contacts will be closed and the solenoid energized to notch the mechanism one position. This can be done by the tapered point of the pin |30 riding upon the surface of the groove in which it is shown.

If, however, it is desired to manually adjust one of the traveling studs, the shaft I I2 may be pulled outwardly to bring the gear |22 into engagement broken by accidental solenoid operation while the gears are in engagement. This also shows means for 'observing to what station the device is tuned.

We claim:

1. In tuning mechanism, means for tuning a K radio receiver to diilerent stations, longitudinally movable means connected to the tuning means, a rotatable drum mounted adjacentthe longitudinally movable means and having its axis parallel thereto and a plurality of members projecting radially from the drum at different angular locations to engage the longitudinally movable means and cause it to move as the drum rotates.

2. In tuning mechanism, a longitudinally movable means for tuning a radioy receiver. a rotatable drurn mounted adjacent the longitudinally movable means and having its axis parallel thereto. a plurality of axially adjustable means projecting beyond the drum and angularly spaced, divergent means mounted on the longitudinally movable means engageable by the projecting means on the drum whereby as the drum rotates the 'projecting means engages the divergent means to cause the longitudinally movable means to move and tune the set.

3. In tuning mechanism, means for tuning a radio receiver, a longitudinally movable bar connected thereto, a pair of divergent arms mounted on said bar, a rotatable drum mounted with its axis parallel to the bar and adjacent thereto with the arms extending substantially tangentially to the drum. and a plurality of axially adjustable projectlble means carried by the drum in different angular positions capable oi engaging the diverging arms sequentially and means for rotating the drum whereby as the different projectible means engage the arms the longitudinally movable means will assume different positions and the receiver will be tuned to different stations.

4. In tuning mechanism. means for tuning a radio receiver, longitudinally movable means connected thereto. a pair of divergent arms connected to the means. a rotatable drum mounted adjacent the means with the arms extending substantially tangential thereto, means to rotate the drum, a plurality of axially adjustable means carried at different positions of the circumference ofthe drum, cylindrical projections on the last-named means to'engage the divergent arms and force the longitudinal means in the direction of its axis until the throat thereof is reached as the drum rotates and means to allow the proactions to pass through the throat.

5. In tuning mechanism, means for tuning al radio receiver. a longitudinally movable bar connected to said means, a pair of spaced divergent arms mounted on lsaid bar. a rotatable drum mounted adjacent said bar with the arms extendinlglribstantially tangentially to said drum. a pl ty ot means movable axially o! the drum mounted at different angular positions adjacent the periphery thereof and adapted to engage the j arms sequentially as the drum is turned, step-bystep means for rotating the drum. the length of each step being the arcuate distance between the axially movable means. whereby the bar is moved longitudinally and the receiver tuned as the ,drumisrotated 6. In tuning mechanism. means for tuning a radio receiver, a longitudinally movable bar connected thereto, a pair of spaced diverging members mounted' on said bar, a rotatable drum mounted adjacent the bar with the diverging members substantially tangent thereto. a plurality oi arcuately spaced threaded shafts rotatably f mounted adjacent the periphery of the drum, traveling indexing assemblies mounted-on leach shaft capable of moving axially betwen the ends of the drumand engaging the spaced diverging members at one position of travelr gear means mounted'coa one end of each of the shafts, step- |by-step means 'to rotate the drum, each step being the arcuate distance between adjacent index assembliesand manual rotatable means capable of being brought into engagement with the gear means, on the threaded shaft which lis in position to 'index whereby the setting of the traveling assembly on that threaded shaft may by-step means for rotating the drum, the length of each step being the arcuate distance between the axially movable means, whereby the bar is moved longitudinally and the receiver tuned as the drum is rotated, and locking means for holding said rotatable drum in indexed position which is released upon movement of the step-by-step driving means. A

LUDWIG FIGHTER. EDWARD KAEGI.

for tuning a v 

